Adjustable atomizer flame photometer



United States Patent inventors Rand E. Herron Stamford, Conn.;

Edward W. Larrabee, Bronxville; Carl V. Johnson, Baldwin, N.Y.

July 3, 1968 Dec. 29, 1970 Technicon Corporation Ardsley (Chauncy), N.Y.

a corporation of New York Appl. No. Filed Patented Assignee ADJUSTABLE ATOMIZER FLAME PHOTOMETER 4 Claims, 3 Drawing Figs.

US. Cl 239/338,

356/187, 356/85, 356/87 11:11.11: m Field ofSearch..... 356/187,

[56] References Cited UNITED STATES PATENTS 2,532,687 12/1950 Weichselbaum 356/187 3,074,309 l/1963 Exley 356/87X 3,137,759 6/1964 lsreeli 356/187 Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Thomas C. Culp, Jr. Attorney-Harry Cohen ABSTRACT: A preatomizer spectral flame burner has a sample tube whose outlet is disposed within a carrier gas conduit terminating in a nozzle. The spacing between the outlet of the sample tube and the outlet of the nozzle is adjustable during the normal operation of the analyzer system, including the burner. Means are provided to withdraw the outlet of the sample tube beyond the gas inlet to the nozzle, whereby positive gas pressure is developed in the sample tube, which is adapted to blow out any obstruction in the sample tube.

PATENTEU nEces I976 SHEET 1 BF 2 l s NNR m a TQM N am. E w 0 v a Z Tu IMRW A Rum i hw yw ADJUSTABLE ATOMIZER FLAME PHOTOMETER FIELD OF THE INVENTION This invention relates to spectral flame burners for providing a spectral flame for the quantitative analysis of various liquids with respect to one or more substances therein. The analytical technique involved may utilize either emission or absorption of light of a significant wavelength.

BACKGROUND OF THE INVENTION Spectral flame burners which atomize a sample liquid and carry the sample liquid into a main flame for vaporization are well known. In most of the prior art burners, both the fuel gas and the combustion supporting gas are supplied under significant pressure to the burner. Such burners are illustrated in US. Pat. Nos. 2,562,874; 2,714,833 and 3,137,759. These burners all use the gas flow at the base of the flame over a sample tube to aspirate the sample up the sample tube into the flame. There the sample is broken into droplets, some of which are small, some of which are large. When any large droplets are vaporized, the flame is pulsed thermally and mechanically, resulting in a flame which is uneven in intensity. Other burners are illustrated in U.S. Pat. Nos. 2,753,753 and 2,858,729. These burners use a preatomization arrangement wherein oxygen under pressure flows over a sample tube to aspirate the sample into the oxygen flow and to break the aspirated sample into droplets. The droplet containing oxygen flow then strikes a baffle which contacts and collects the larger droplets. However, the mixing of the oxygen flow occurs at the base of the flame. This mixing tends to be uneven, and this results in a flame which is uneven in intensity. In application Ser. No. 586,685, filed on Oct. 14, 1966, by J. Isreeli and E. W. Larrabee, assigned to a common assignee, there is disclosed a spectral flame burner which is adapted to utilize a fuel gas supplied at a relatively low pressure and which will pass only relatively small droplets of sample into the flame. In that burner, the sample is positively transmitted through the sample tube, as by a peristaltic pump, into an airstream which entrains droplets of the sample liquid, and which carries the smaller droplets into the flame.

SUMMARY OF THE INVENTION It is an object of this invention to provide an improved burner of the type disclosed in SerfNo. 586,685 supra, wherein the volumetric rate at which sample is fed into the flame may be adjusted, as for maximum sensitivity; and wherein any obstructions carried into the sample tube may be flushed out expeditiously, without disassembly of the burner.

A feature of the invention is the provision in a preatomizing spectral burner of a sample tube whose outlet is disposed within a carrier gas conduit terminating in a nozzle, and wherein the length of the interaction path, i.e., the spacing between the outlet of the sample tube and the outlet of the nozzle, may be adjusted during the normal operation of the analytical system including the burner. An additional feature is the provision of means to withdraw the outlet of the sample tube beyond the gas inlet to the nozzle, whereby positive gas pressure is developed in the sample tube which is adapted to blow out any obstruction in the sample tube.

BRIEF DESCRIPTION OF THE DRAWING section, taken along DESCRIPTION OF THE PREFERRED EMBODIMENT The flame photometer main assembly includes a burner assembly 10; a mirror assembly, a sample emitted light detector assembly, an infrared flame detector assembly, a flame igniter assembly, and a chimney, all not shown, but disclosed in Ser. No. 586,685, supra.

The burner assembly 10 includes a tubular main body 20, having in longitudinal axial alignment a lower mixing chamber 22, and upper burner tube receiving bore 24, two intermediate chambers 26 and 28, an upper annular flange 30 and a lower annular flange 32. A baseplate 34 is releasably sealed to the lower flange 32 by a plurality of thumb screws 36 and an O- ring 38. The main body also has three bosses and bores for these fittings, i.e., sample liquid, air and gas. The gas fitting 40 is mounted into the main body on a transverse axis which is displaced slightly from a radius of the main body so that the inner wall of the mixing chamber 22 intersects the longitudinal axis of the gas fitting at an angle which is less than The sample fitting 42; is disposed in the same horizontal plane as the gas fitting 40? and has a longitudinal axis which is chordal to the mixing chamber 22. The air fitting 44 is disposed above, and in the same vertical plane as the sample fitting 42. The bore of the air fitting 44 communicates with a vertical longitudinal bore 46 provided in a rib 48 formed in the wall of the main body. The lower end of the bore 46 communicates with the bore 50 in the main body through which the sample fitting is disposed. The upper end of the bore 46 communicates with a bore 52 in the top plate 54 which is'screwed to the upper flange 30 by machine screws, not shown. A short tube 56 is disposed within the upper portion of the bore 46 to restrict the flow of air from the air fitting 44 to the bore 52.

A burner tube 58 is sealed within the upper bore 24 of the main body and extends upwardly, through and beyond a central bore 60 in the top plate 54. The upper end of the burner tube is closed by a burner cap 62 which has a plurality of perforations 64 and a burner tip 66.

An auxiliary air manifold block 68 is disposed on the top plate 54 around the upper end of the burner tube. The block is closed by an annular plate 70, whose upper surface is coplanar with the upper surface of the burner cap 62. The block 68 includes a central bore 71, an outer lower flange 72 which rests on the top plate 54 and is sealed thereto by an O-ring 74 and a plurality of machine screws, not shown, an intermediate an nular recess 76 to support the chimney, not shown, and an O-ring 78 to seal the block to the chimney. The block also includes an outer lower annular cavity 80, an inner lower annular cavity 82, and an upper annular cavity 84. The bore 52 communicates with the cavities 82 and 80 by a gap between the plate 54 and the block, and the cavity 82 communicates with the cavity 84 by a plurality of longitude bores 88. The cavity 84 has an upper annular opening 90. An O-ring 92 seals the gap between the exterior of the burner tube 58 and the central bore 71.

As seen in FIG. 3, the sample fitting includes an atomizer body having a longitudinal bore 102 extending into a left enlarged bore portion 104 which is internally threaded at 106, and a diametrical bore 108. An intermediate body 110, which is externally threaded at 112, is engaged in part within the bore portion 104 and may be longitudinally advanced or retracted therein. The body has a longitudinal bore 114 which is internally threaded at 116 to receive an atomizer capillary assembly 118. The capillary assembly 118 includes a leur lock 120 having a central bore through which an outer tube 122 is sealed, and into which an inner tube 124 is sealed. The right end of the bore 102 of the body 100 is internally threaded at 128 to receive an atomizer tip or nozzle 130. The tip includes a rightmost head end 132, an intermediate externally threaded portion 134 which engages the internal threads 128 of the bore 102, and a leftmost portion 136, which is of reduced external diameter to provide an air gap between itself 75 and the interior wall of the bore 102. The tip has a longitudinal bore having a leftmost portion 138 of a diameter adequate to receive and provide a slidable reasonably close fit with the rightmost end of the outer tube 122; and intermediate portion 140 of a smaller diameter adequate to receive and provide an air gap with the right end of the inner tube 124', and a rightmost portion 142 of a yet smaller diameter adequate to receive and provide a small air gap with the rightmost end of the inner tube 124. A plurality of radial bores 144 is provided through the intermediate tip portion 134 into the intermediate bore portion 140. Thus, air may pass through the diametrical bore 108, through the gap between the outer tube 122 and the bore 102, through the gap between the leftmost tip portion 136 and the bore 102; through the radial bores 144; through the gap between inner tube 124 and the bore portion 140; through the gap between the inner tube 124 and the bore portion 142; and out the tip.

A yoke 150 is clamped onto the intermediate body, and an auxiliary block 152 is fixed thereto by a machine screw 154. A spur gear 156 is fixed on a shaft 158 whose right end is journaled in a bore 160 in the yoke 150, and whose left end in 'journaled through and beyond a bore 162 inthe block 152. A

flexible shaft 164 is fixed to the left end of the shaft 158 by a set screw 166. A spur gear 166 is fixed onto the intermediate body 110, and meshes with the gear 156. Rotation of the flexible shaft 164 causes rotation of the gear 156, which causes rotation and longitudinal movement of the gear 166, the intermediate body 110, the leur lock 120 and the inner and outer tubes 122 and 124, and thus adjustment of the relative longitudinal position of the end of the inner tube 124 within the tip 130.Adequate travel is provided so that the right end of the tube 124 may be adjusted to any longitudinal position at least between l coplanar with the right face of the tip 130 and (2) to the left of the radial bores 144. Overtravel prevention is provided by a pin 168 fixed through the gear 166 and adjusted to laterally engage with a pin 170 fixed in the block 152 or a pin 172 fixed in the yoke 150.

The sample liquid which is to be examined is displaced into the left end of the tube 124 by a positive displacement pump such as is shown in U.S. Pat. No. 2,935,028. Four O-rings 180, 182, 184 and 186 seal the bore 46 into communication with the bore 108 and 102. Thus, when compressed air is provided at the air fitting 44, most of that air passes downwardly through the bore 46, through the bore 108, through the bore 46, through the bore 108, through the bore 144, past the right end of the tube 124, and out the tip 130. When the right end of the tube 124 is disposed to the right of the radial tubes 108, preferably within the inner bore portion of 42 of the tip, as the air passes the end of the tube it atomizes the sample liquid being discharged therefrom and carries droplets of the sample liquid into the mixing chamber 22. Since the sample fitting is located on a chord with respect to the mixing chamber, the air and droplet flow strikes the inner surface of mixing chamber in a clockwise direction, as seen in FIG. 1. The larger, heavier droplets of liquid strike and flow along the wall of the mixing chamber 22. To preclude continued circulation of this liquid around the chamber to the gas inlet, a vertical channel 200 is cut into the wall of the chamber, upstream clockwise, of the gas inlet. The channel in cross section has hook" shape to trap the liquid and to cause it to flow downwardly to the baseplate 34 and through a drain outlet 202. The floor 204 of the baseplate has a conical depression, with a groove 206 leading from the apex to the outlet. In order to reduce the size of the droplets carried upwardly into the flame, an insert assembly comprising a tube 210 and a ring 212 may be inserted between the mixing chamber 22 and the tube 58. Only the lightest and, therefore, the smallest, of the droplets will be carried in the center of the rising vortex of gas and droplets and will'clear the ring 212 and pass upwardly through the insert. The heavier droplets will be trapped by the ring and pass out the drain.

The fuel gas fitting 40 includes a body 224 and a hole sealed therethrough, which is coupled to a source of relatively low pressure fuel gas. The outlet end 228 of the hole 226 is closed and a longitudinal line of radial bores 230 is provided for the discharge of the gas into the mixing chamber. The line of bores is oriented to be on the lee side of the hole with respect to the clockwise flow of the relatively high pressure air from the atomizer tip 132, so that a space of relatively low pressure is formed adjacent these bores, into which space the relatively low pressure gas may flow. The air, sample vapor droplets and the gas swirl around in the mixing chamber and uniformly intermix. The mixture, still swirling, rises up into the burner tube 58. Three symmetrically disposed fins 136 are provided projecting from the inner surface of the burner tube to deflect the swirling flow into a linear flow up the burnertube and out the perforations 64. Since the tube 126 is at an acute angle to the clockwise air and sample flow, any sample which settles out of the hole will be blown along the tube to the body 224 and will drain off onto the wall of the mixing chamber.

When compressed air is provided at the air fitting 44, some I of that air passes upwardly through the bore 46 and the constricting tube 56 into the two lower annular cavities 82 and 80, and thence into the upper annular cavity 84 and out the annular opening to provide a uniform sheath of air around the main flame from the perforations 64. This sheath stabilizes the main flame by girdling it and by supplying excess oxygen for complete combustion.

The burner tip 66 projects into the blue cone of the flame and is heated thereby. The tip is in contact with the burner cap 62 and at the start of operation, rapidly brings the cap to thermal equilibrium to stabilize the preheating of the gas mixture.

In the event that an obstruction is carried into the inner tube 124 and jams in, it may be removed without disassembly of the bores now develops a positive pressure into the tube 124 which is adequate to blow out such obstructions.

In use it has been found that maximum sensitivity is achieved by a delicate adjustment of the spacing of the right end of the sample tube 124 within and from the right end of the tip, and this is readily accomplished by manual adjustment of the flexible shaft when the burner is started and stabilized at the commencement of the days operation.

While we have shown and described the preferred embodiment of the invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

We claim:

1. A spectral flame photometer burner, comprising:

an upstanding burner tube having an upper outlet and a lower inlet;

a substantially circular mixing chamber coupled to said burner tube inlet;

a conduit, terminating in a nozzle, disposed within said chamber, having an intermediate inlet, whereby a first gas, when supplied through said inlet and out through said nozzle has a path of flow which swirls around said chamber and up said burner tube;

a sample tube, having an inlet external to said conduit, an intermediate portion, sealed to said conduit, and having an outlet disposed within said conduit; and

means for providing relative movement between said sample tube outlet and said conduit, whereby said tube ou'tlet may be adjustably disposed between said conduit inlet and said nozzle, whereby a sample liquid, when transmitted into said sample tube inlet and out said outlet, will be carried along by the first gas and atomized into droplets through said nozzle, and, alternatively, may be disposed to one side of said conduit inlet remote from said nozzle, whereby the first gas will develop a positive pressure into said sample tube inlet.

2. A burner according to claim 1 wherein said relative movement providing means includes:

first driven means coupled between said conduit and said sample tube for providing longitudinal movement therebetween; and second driving means drivingly coupled to said first driven means and operable while said burner is in operation. 3. A burner according to claim 1 wherein: said sample supply tube is tr threaded within and to said conduit and has a first gear fixed thereto, whereby rotation of said first gear causes rotation of said tube and longitudinal movement, with respect to said conduit; and further including a second gear drivingly meshed with said first gear, and coupled to additional means for driving an said second gear and adapted for use while said burner is in operation.

4. A burner according to claim 1 wherein:

said nozzle has its longitudinal axis on a geometric chord to the circle of said chamber, whereby the first gas, when supplied under relatively high pressure through said nozzle has a path of flow which strikes the interior wall of said chamber and swirls around within said chamber; and

a vertical groove in said interior wall of said chamber, disposed downstream of the impact point of said first gas flow, having a hook-shaped cross section, whereby to trap and channel downwardly any liquid flowing on said interior wall from said impact point. 

